Multi-stage pressure control dump valve assembly for torque control operations

ABSTRACT

A “dump” or bypass system for use with fluid-powered tongs utilized to apply torque forces to threaded connections during pipe installation operations. A computer having a data processor monitors and analyzes rotations of, and torque forces applied to, pipe sections being assembled. A pilot-operated relief valve actuates a bypass dump valve. The bypass system operates in “real-time”, quickly and efficiently dumping fluid supplying a power tong—and stopping the application of torque forces on a pipe section—once a predetermined measured torque value is achieved.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention pertains to a method and apparatus for controlling torque forces during pipe string assembly operations in various industrial applications such as, for example, in the oil and gas industry. More particularly, the present invention pertains to a dump valve system for use in torque control systems utilized during make-up of threaded collar and pipe connections.

2. Brief Description of the Prior Art

During well drilling and completion operations, pipe (such as, for example, drill pipe, casing or tubular workstring) can be installed into a well bore in a number of separate sections of substantially equal length, commonly referred to as “joints.” The joints, which generally include threaded connections at each end, are typically joined end-to-end at the earth's surface (frequently from a drilling rig) in order to form a substantially continuous “string” of pipe that reaches downward into a well bore.

As part of the pipe installation process, additional sections of pipe are added to the upper end of the pipe string at the earth's surface (typically at a drilling rig or other similar facility) in order to increase the overall length of the pipe string and its penetration depth in a well bore. The addition of pipe sections at the earth's surface is repeated until a desired length of pipe is inserted into the well bore.

The process of installing a string of pipe in a well is typically commenced by lowering a first section of pipe into a wellbore at a drilling rig floor, and suspending said section of pipe in place using a set of “lower slips.” In this position, the uppermost end of said first section of pipe is generally situated a few feet above the rig floor. Thereafter, a second section of pipe is lifted within a drilling rig derrick and suspended vertically within said derrick; the second section of pipe is then positioned in linear alignment above the first section of pipe suspended there below.

After said pipe sections are axially aligned with each other, the lower end of said hanging second pipe section is then lowered or “stabbed” into the upper end of said first pipe section. Thereafter, torque is applied to the second pipe section using a power tong or other device, in order to make up (that is, screw together) mating threaded connections of said first and second pipe sections. In most cases, said power tong is powered using hydraulic or other fluid.

After said threaded connection members are joined and said pipe sections are attached in mating relationship, said lower slips can be disengaged. The attached pipe sections (suspended from a rig's traveling block or top drive unit) can be lowered further into the well. After said attached pipe sections are lowered to a desired position, said lower slips can be reengaged in order to safely suspend such pipe within the well bore. The process can then be repeated until a desired length of pipe is run into the well.

During such pipe make-up/connection and installation operations, it is critically important to control torque forces applied to said pipe sections. If such applied torque is too high, the mating threaded connection members can become damaged such as, for example, by over torque-ing or thread galling. If such applied torque is too low, the mating threaded connection members may not fully engage with one another, thereby affecting the pressure integrity and/or axial load supporting capacity of the threaded connection. As a result, torque control systems are frequently employed to ensure proper application of torque during such pipe make-up operations.

Conventional torque control systems used during pipe installation operations generally comprise a rotational sensor (frequently mounted to a power tong) to measure pipe rotation during connection make-up, a load cell or other torque measurement sensor to measure the amount of applied torque on the connection, and a computer that logs and compares such measured torque to the accumulated turns. The computer then uses this information to predict the torque rise as the threaded connection is made up. When the computer determines that such optimum connection torque has been reached, the computer sends a signal to said power tong assembly to cease the application of torque on the pipe.

Specifically, said computer can send a “dump” signal to a valve that is connected to an input conduit supplying pressurized power fluid to said tong, as well as an outlet conduit extending from said tong into a reservoir or storage tank, thereby forming a bridge between said conduits and a fluid bypass to said tong. When said valve receives a “dump” actuation signal from said computer, said valve opens, thereby allowing pressurized fluid (that was previously driving the tong) to bypass the tong and be diverted via said output conduit to said tank. When said “dump” process is triggered, the tong ceases applying torque forces to the pipe.

Typically, such conventional fluid dump valves are operated using an electronic (or partially electronic) system. In most cases, the computer sends an electronic signal to a solenoid. The solenoid is actuated which, in turn, shifts said valve. As discussed above, when said valve is shifted in response to a “dump” signal from the computer, fluid flow from the inlet or supply line of the tong is diverted to the outlet or tank line, thereby bypassing said tong.

Due to the mechanics of the solenoid and valve, such dumping action typically includes a built-in time delay; frequently, this delay can be in a range between 50 ms and 100 ms. In some cases, specialized computer software includes a “look ahead” feature that attempts to anticipate when optimal torque levels will be reached. However, when mating threaded connection members are cross threaded, or when a galling problem is encountered, torque forces can rise very rapidly. Thus, even with such a “look ahead” system, a dump signal may not be sent fast enough to stop thread damage from occurring.

Thus, there is a need for a quick, reliable and effective system for controlling torque applied to threaded connections during the pipe installation process. The system should permit the dumping of pressurized power fluid supplying a power tong or other torque application device to occur, without significant delay, when predetermined measured values are obtained.

SUMMARY OF INVENTION

In a preferred embodiment, the present invention comprises a “dump” system for use with hydraulically powered tongs utilized to apply torque to threaded connections during pipe installation operations. The dump system of the present invention is controlled by a computer having a data processor that can monitor and analyze rotations and torque of each pipe section that is being assembled within a pipe string. Specifically, the dump system of the present invention quickly and efficiently dumps hydraulic energy that is feeding a power tong once a predetermined optimum torque for a threaded connection is achieved.

In a preferred embodiment, the present invention comprises a pilot-operated relief valve that uses the same hydraulic fluid power that is powering a hydraulic tong as a power source to shift a bypass dump valve. The dump system of the present invention can operate in “real-time” with little or no delay time observed with conventional dump systems. For example, the dump system of the present invention can actuate in as little as (2) milliseconds, thereby allowing a cross-threading incident to be stopped before any damage occurs to the threads.

Additionally, in a preferred embodiment, the dump system of the present invention permits maximum operating pressure to be set at a significantly lower level than conventional dump systems. Such lower pressure beneficially allows for the maximum system pressure to be set at or below a maximum torque capability of a threaded connection, therefore providing a redundant safety factor in an event of a computer failure or other unanticipated problem during pipe connection operations.

Although the torque control dump system of the present invention is used primarily in connection with rig-based pipe installation operations (that is, in the field), it is to be observed that said torque control dump system can also be used with bucking units or other pipe connection operations performed in shops, facilities or other locations.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing summary, as well as any detailed description of the preferred embodiment, is better understood when read in conjunction with the drawings and figures contained herein. For the purpose of illustrating the invention, the drawings and figures show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed in such drawings or figures.

FIG. 1 depicts a schematic illustration of a preferred embodiment of the dump valve bypass assembly of the present invention incorporated within a tubular assembly system.

FIG. 2 depicts a schematic illustration of a preferred embodiment of a multi stage dump valve assembly of the present invention.

FIG. 3 depicts a schematic illustration of a preferred embodiment of a dump valve remote control assembly of the present invention.

FIG. 4 depicts a schematic illustration of a preferred embodiment of the dump valve assembly of the present invention during make-up of a threaded pipe connection.

FIG. 5 depicts a schematic illustration of said dump valve assembly of the present invention when a dump signal is sent from a torque-turn computer to actuate said dump valve assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 depicts a schematic illustration of a preferred embodiment of the dump valve bypass assembly of the present invention incorporated within a tubular assembly system used, for example, during the installation of tubular goods in a well. Numbered elements depicted in FIG. 1 comprise the following:

-   -   100—multi-stage dump valve assembly     -   200—dump valve remote control assembly     -   300—a computer having a data processor for controlling and         monitoring applied torque forces and pipe turns     -   301—rotary encoder/sensor (measures speed, direction and         rotation of pipe)     -   301 a—rotary encoder signal line     -   302—load cell/sensor (measures torque forces applied to pipe by         tong)     -   302 a—load cell signal line     -   401—hydraulic pump (fluid pressure source)     -   402—hydraulic fluid reservoir     -   501—manually operated directional control valve mounted on or         near tong (manually controls speed and direction of power tong         motor)     -   502—power tong hydraulic motor—supplies power to tong unit         needed to “make-up” or screw together mating threaded pipe         connections

Still referring to FIG. 1, a fluid power source 401 is in fluid communication with motor 502 used to drive a torque imparting device, such as a set of conventional power tongs, used to assemble mating threaded connection members of pipe sections. Although other fluid types and component configurations can be employed without departing from the scope of the present invention, in a preferred embodiment such power fluid comprises hydraulic fluid.

In such configuration, motor 502 is hydraulically powered, and fluid power source 401 comprises a hydraulic pump. Hydraulic fluid is supplied from said fluid power source (pump) 401 through fluid supply line or conduit 109 and manually operated control valve 501, to tong hydraulic motor 502. Hydraulic fluid leaves said tong hydraulic motor 502 via hydraulic outlet line or conduit 110, through manually operated control valve 501 to hydraulic fluid reservoir 402. Although not depicted in FIG. 1, it is to be observed that hydraulic fluid returned to hydraulic fluid reservoir 402 can be filtered and/or otherwise conditioned and returned to fluid power source (pump) 401 as part of a closed-loop hydraulic fluid system.

Load cell 302 serves as a sensor to measure torque forces applied by tong motor 502 (via a set of power tongs) to a pipe section having a threaded connection member, which is being threadably connected to another mating pipe section. Data measured by load cell 302 is transmitted via load cell signal line 302 a, which typically comprises a data conducting wire, to a computer 300 having a data processor. Similarly, rotary encoder member 301 serves as a sensor to measure speed, direction and/or rotation of said section of pipe being threadably connected to another mating pipe section. Data measured by rotary encoder member 301 is transmitted via rotary encoder signal line 301 a, which is typically a data conducting wire, to said computer 300.

Computer 300 is operationally connected to dump valve remote control assembly 200 which, in turn, is operationally connected to multi-stage dump valve assembly 100 of the present invention as more fully described below. Said multi-stage dump valve assembly 100 is in selective fluid communication with hydraulic supply conduit 109 and hydraulic outlet conduit 110.

FIG. 2 depicts a schematic illustration of said multi-stage dump valve assembly 100 of the present invention. As depicted in FIG. 2, said multi-stage dump valve assembly 100 includes, without limitation, a piloted main relief valve, a pneumatic three way valve, a full pressure pneumatic dump signal, a power tong, and a hydraulic power unit. Numbered elements depicted in FIG. 2 comprise the following:

-   -   101—piloted relief valve assembly     -   101 a—hydraulic pilot control line     -   101 b—hydraulic pilot sensing line     -   101 c—hydraulic bridge/bypass (pressure) line     -   101 d—hydraulic bridge/bypass (return) line     -   102—pneumatic piloted, pilot relief valve assembly     -   102 a—pilot relief inlet from main relief valve     -   102 b—pilot relief return     -   102 c—air pilot inlet, controlled air supply     -   102 d—junction     -   103—pneumatic three way valve (normally open)     -   103 a—three way valve regulated air inlet     -   103 b—three way valve regulated air outlet (to 102 c air pilot)     -   103 c—three way valve exhaust port     -   103 d—three way valve air pilot, full pressure unregulated pilot         signal inlet     -   104—full pressure pneumatic dump signal conduit     -   105—reduced pressure regulated pilot air signal (used to set         hydraulic system pressure on pilot valve 102)     -   106—hydraulic pressure sample line for remote gauge     -   107—power tong conduit, tank/reservoir side     -   108—power tong conduit, supply side     -   109—hydraulic supply conduit from hydraulic power source     -   110—hydraulic outlet conduit to reservoir

FIG. 3 depicts a schematic illustration of a preferred embodiment of the dump valve control assembly 200 of the present invention. Numbered elements depicted in FIG. 3 comprise the following:

-   -   200—dump valve control assembly     -   201—solenoid operated three way air valve (used to send dump         signal to three stage dump valve)     -   201 a—electrically operated solenoid     -   201 b—electric dump signal from torque control computer 300     -   202—precision air regulator (used to set pressure on valve 102)     -   203—main filter/regulator/lubricator (ensures rig air coming in         as at proper cleanliness and pressure)     -   203 a—rig air inlet to system     -   203 b—pneumatic conduit to solenoid operated three way air valve         201     -   203 c—pneumatic conduit to precision air regulator 202     -   104—full pressure pneumatic dump signal conduit     -   204—hydraulic pressure gauge (reads output hydraulic pressure         from sampling line 106)     -   105—reduced pressure regulated pilot air signal (used to set         hydraulic system pressure on pilot valve 102)

FIG. 4 depicts a schematic illustration of a preferred embodiment of the dump valve assembly of the present invention during assembly of a threaded pipe connection, while FIG. 5 depicts a schematic illustration of said dump valve assembly when a dump signal is sent from a torque-turn computer to actuate said dump valve assembly.

Referring to FIG. 1, rig air blower 600 generates pneumatic air pressure which is sent to dump valve control assembly 200. Referring to FIG. 3, said pneumatic air pressure passes through inlet 203 a into main filter/regulator/lubricator 203, which ensures that rig air entering the pneumatic control system meets desired cleanliness and pressure requirements.

Said pneumatic air pressure exiting filter/regulator/lubricator 203 is split via conduits 203 b and 203 c; pneumatic air pressure in conduit 203 b is sent to solenoid operated three way air valve 201 having electrically operated solenoid 201 a, while pneumatic air pressure in conduit 203 c is sent to precision air regulator 202. Electrical conducting line 201 b provides an electric dump signal from torque control computer 300 to electrically operated solenoid 201 a of three way air valve 201. Hydraulic pressure gauge 204 reads output hydraulic pressure from sensing line 106.

Referring to FIG. 2, a hydraulic relief valve 101 is set with a pneumatic operated pilot relief valve 102; actuation of pneumatic pilot relief valve controls operation of hydraulic relief valve 101. Pneumatic pressure provided via conduit 105 (from precision air regulator 202) is a regulated pressure signal that regulates the hydraulic pressure based on a desired ratio (typically approximately 50:1) that allows for a low pressure pneumatic signal to convert into a high pressure hydraulic pressure signal. (As a result of this ratio, a relatively small amount of pneumatic pressure can offset a much greater amount of hydraulic pressure). In order to provide for a dumping action that can be applied at a predetermined torque measurement, the pneumatic signal line 105 is broken by an air piloted three way valve 103.

During normal operation, a pneumatic pressure signal from conduit 105 passes through valve 103 at inlet port 103 a to outlet port 103 b, and is connected to pilot relief valve 102 at pilot valve inlet 102 c. Load cell sensor 302 measures torque forces applied by tong motor 502 (via a set of power tongs) to a pipe section having a threaded connection member, which is being threadably connected to another mating pipe section.

Data measured by load cell 302 is transmitted via load cell signal line 302 a to a computer 300 having a data processor. Similarly, rotary encoder member 301 serves as a sensor to measure speed, direction and/or rotation of said section of pipe being threadably connected to another mating pipe section, while data measured by rotary encoder member 301 is transmitted via rotary encoder signal line 301 a to said computer 300.

When a predetermined torque measurement (as sensed by load cell 302) has been achieved, an electronic signal is sent from computer 300 via line 201 b to electrically operated solenoid 201 a. Said electrically operated solenoid 201 a actuates valve 201. When this occurs, a pneumatic dump signal is sent via dump signal conduit 104 to full pressure unregulated pilot signal inlet 103 d of pneumatic three way valve 103. Once said dump signal is applied to valve 103, said three-way valve 103 shifts, thereby connecting valve air outlet 103 b to exhaust port 103 c, which is vented to atmosphere.

With said valve 103 shifted, regulated air pilot signal via line 105 is blocked. As such, regulated pneumatic pressure from line 105 that was holding pneumatic pressure on air pilot inlet 102 c of pilot relief valve assembly 102 is vented, and pneumatic pressure from line 105 is no longer held on air pilot inlet 102 c. Without such pilot air held on pilot relief valve assembly 102, said relief valve assembly 102 shifts. When this occurs, pneumatic pressure on piloted relief valve assembly 101 is bled off, thereby causing said piloted relief valve 101 to open.

With said piloted relief valve assembly 101 open, hydraulic fluid in hydraulic supply conduit 109 (from hydraulic power source 401) flows through hydraulic bridge or bypass (supply) conduit 101 c, open relief valve 101, and hydraulic bridge or bypass (return) conduit 101 d. Said hydraulic fluid exits said conduit 101 d via return line 110. In this manner, supply hydraulic fluid used to power tong motor 502 (which imparts torque forces to a threaded connection of a pipe section) can be quickly and efficiently dumped or bypassed around said motor 502 in order to cease the application of torque to said threaded connection.

In a preferred embodiment, utilizing the same hydraulic energy that is also used to operate the power tong (and which is already present in the system) in order to shift the bypass/relief valve once pneumatic pilot pressure 105 is vented from pilot valve 102 c insures a fast-acting relief valve actuation that quickly opens the bypass/relief valve and removes the hydraulic energy (supply) from the power tong during thread assembly operations. Conventional dump valves use components that must be energized in order to supply the force necessary to shift a bypass or “dump” valve. The present invention utilizes hydraulic energy that is already present in the system. The same hydraulic pressure used to power the tong (which is already present in the system) also supplies the energy to open the bypass valve; unlike conventional dump systems, no additional energy must be added to actuate the bypass valve.

Additionally, valve 103 can be located in close physical proximity to valves 102 and 101 (typically at a distance of 12 inches or less), thereby reducing travel time for pneumatic signal pressure. This distance factor, together with the fact that a regulated low pressure pneumatic (air) signal travels faster than a hydraulic fluid, further ensures a very quick actuation of bypass valve 101. Moreover, the use of a desired ratio (typically approximately 50:1) of hydraulic pressure to pneumatic pressure ensures that a relatively small change in pneumatic pressure results in a much greater impact on hydraulic pressure (or the ability to offset much higher hydraulic pressures with relief valve 101).

The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention. 

What is claimed:
 1. A fluid pressure bypass assembly for controlling the application of torque to a threaded pipe connection comprising: a) a tong unit adapted to impart torque to said threaded connection; b) a supply conduit adapted to supply hydraulic fluid to an inlet of said tong unit; c) an outlet conduit adapted to receive hydraulic fluid from an outlet of said tong unit; d) a bypass conduit extending between said supply conduit and said outlet conduit; e) a pilot controlled hydraulic valve disposed along said bypass conduit, wherein said pilot controlled hydraulic valve is adapted to shift between a first closed position and a second open position in response to a pneumatic pilot signal; f) a torque sensor adapted to measure torque applied to said threaded connection by said tong unit; and g) a computer having a data processor, wherein said computer receives data from said torque sensor and shifts said pilot controlled hydraulic valve from said first position to said second position to bypass said tong unit when said torque sensor measures a preselected torque value.
 2. The fluid pressure bypass assembly of claim 1, wherein said torque sensor comprises a load cell.
 3. The fluid pressure bypass assembly of claim 1, further comprising a rotary encoder adapted to measure speed, direction and/or rotation of said threaded connection, and wherein said computer receives measured data from said rotary encoder.
 4. A fluid pressure bypass assembly for controlling the application of torque to a threaded pipe connection comprising: a) a tong unit adapted to impart torque to said threaded connection; b) a supply conduit adapted to supply hydraulic fluid to an inlet of said tong unit; c) an outlet conduit adapted to receive hydraulic fluid from an outlet of said tong unit; d) a bypass conduit extending between said supply conduit and said outlet conduit; e) a pilot controlled hydraulic valve disposed along said bypass conduit, wherein said pilot controlled hydraulic valve is adapted to shift between a first closed position and a second open position in response to a pneumatic pilot signal; f) an air compressor adapted to provide a pneumatic pilot signal to said pilot controlled hydraulic valve; g) a torque sensor adapted to measure torque applied to said threaded connection by said tong unit; and h) a computer having a data processor, wherein said computer receives data from said torque sensor and interrupts said pneumatic pilot signal to said pilot controlled hydraulic valve, thereby shifting said pilot controlled hydraulic valve from said first position to said second position and bypassing said tong unit, when said torque sensor measures a preselected torque value.
 5. The fluid pressure bypass assembly of claim 4, wherein said torque sensor comprises a load cell.
 6. The fluid pressure bypass assembly of claim 4, further comprising a rotary encoder adapted to measure speed, direction and/or rotation of said threaded connection, and wherein said computer receives measured data from said rotary encoder.
 7. The fluid pressure bypass assembly of claim 4, further comprising: a) a pneumatic supply conduit connecting said air compressor to said pilot controlled hydraulic valve; and b) a pneumatic control valve disposed along said pneumatic supply conduit, wherein said pneumatic control valve is adapted to shift between a first open position and a second closed position.
 8. The fluid pressure bypass assembly of claim 7, wherein said pneumatic control valve is adapted to shift between said first open position and said second closed position in response to an electronic signal from said computer.
 9. The fluid pressure bypass assembly of claim 8, wherein said pneumatic control valve comprises a solenoid operated valve. 